The fineness of features of a semiconductor device has progressed according to a high integration of the semiconductor device. This fineness of features of the semiconductor device requires the finesses of wirings as well as gates.
However, a photo lithography process performed by means of light sources such as ArF, KrF, F2, etc. and the patterning of a photoresist has a limitation for the implementation of the fine pattern of the gate.
This is due to the limitation of an optical system and the limitation the resolution of a photoresist polymer itself.